Loss Measurements Research Articles

Effect of H2S on CO2 Corrosion of Mild Steel in High-Temperature Supercritical CO2 Conditions

The effect of H2S on the aqueous corrosion behavior of mild steel was evaluated at high-pressure and high-temperature (HPHT) conditions at a partial pressure of CO2 of 12 MPa and a temperature of 160°C. The corrosion rate of steel samples was determined by electrochemical and weight loss measurements. The surface and cross-sectional morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction). Results showed that the corrosion rate decreased with time and no significant difference was observed in the presence of 1,000 ppm and 2,000 ppm of H2S at HPHT CO2 conditions. Surface and cross-sectional analyses revealed that the corrosion process was governed by the formation of FeCO3 regardless of the presence of H2S. Furthermore, the corrosion behavior of mild steel in these conditions did not depend significantly on flow velocity.

Active TCC based protection coordination scheme for networked distribution system

A growing interest in the networked distribution system (NDS) can be attributed to multiple advantages in comparison to the radial distribution system (RDS): an improved feeder utilization rate, alleviation in feeder voltage drop and increased receptive capacity of distributed generation (DG). However, adequate protection coordination algorithm including directional comparison trip (DCT) and backup measures for communication loss and directional over-current relay (DOCR) malfunction have yet to exist. This paper alternatively presents a communication-based protection coordination method for the NDS through the new time–current curve (TCC) considering the characteristics of the fault situation. The proposed method enables automatic TCC change according to the location of the protection device in a fault situation regardless of the structure of the distribution system.

Circadian patterns of heart rate variability in fetal sheep after hypoxia-ischaemia: A biomarker of evolving brain injury.

Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and severe neurodevelopmental disability in survivors, including cerebral palsy, although there are no reliable biomarkers to detect at risk fetuses that may have suffered a transient period of severe HI. We investigated time and frequency domain measures of fetal heart rate variability (FHRV) for 3weeks after HI in preterm fetal sheep at 0.7 gestation (equivalent to preterm humans) until 0.8 gestation (equivalent to term humans). We have previously shown that this is associated with delayed development of severe white and grey matter injury, including cystic white matter injury (WMI) resembling that observed in human preterm infants. HI was associated with suppression of time and frequency domain measures of FHRV and reduced their circadian rhythmicity during the first 3 days of recovery. By contrast, circadian rhythms of multiple measures of FHRV were exaggerated over the final 2weeks of recovery, mediated by a greater reduction in FHRV during the morning nadir, but no change in the evening peak. These data suggest that the time of day at which FHRV measurements are taken affects their diagnostic utility. We further propose that circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury. KEY POINTS: Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and probably for disability in survivors, although there are no reliable biomarkers for antenatal brain injury. In preterm fetal sheep, acute HI that is known to lead to delayed development of severe white and grey matter injury over 3weeks, was associated with early suppression of multiple time and frequency domain measures of fetal heart rate variability (FHRV) and loss of their circadian rhythms during the first 3 days after HI. Over the final 2weeks of recovery after HI, exaggerated circadian rhythms of frequency domain FHRV measures were observed. The morning nadirs were lower with no change in the evening peak of FHRV. Circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury.

Coupled thermomechanical FE model of a railway disc brake for friction material wear calculations

The article presents a fully coupled 3D thermomechanical model of a railway vehicle disc brake for calculations of temperature, stress, contact pressure and wear distributions. Five specially designed composite organic friction materials associated with a cast-iron ventilated brake disc were analyzed. The performed computer simulations correspond to the operational parameters of braking carried out on a full scale dynamometer test stand at constant braking power and constant vehicle velocity. These conditions were obtained by correcting the clamping force in relation to changes in the coefficient of friction. In the finite element (FE) model of the disc brake, the pad wear depth distribution was determined on the basis of the Archard's law taking into account the specific wear rate, contact pressure and sliding velocity. To create the numerical model with the geometry deformation allowing for friction material loss due to wear, advanced techniques were adapted. The geometric model of the brake includes the complex shapes of the brake pad holder, brake pad and ventilated disc. The wear constants of the tested friction material were obtained by means of the FE simulation and the measurement of the pad weight loss before and after the test on a full scale dynamometer test stand. The distributions of temperature, stresses, contact pressure and accumulated wear depth, obtained from the finite element analysis, in combination with the measured changes in the clamping force and coefficient of friction during braking, enabled to establish relationships between the properties of materials, operational parameters of braking and geometrical features of the brake components.

The role of soybean meal extracts proteins in the inhibition of mild steel acid corrosion

In this research, the mild steel corrosion inhibition effect of three extracts from soybean meal and a soybean protein commercial sample was examined using mass loss tests, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The anti-corrosive properties of soybean meal extracts were investigated normalizing the peptide/protein amount. The inhibitors were chemically characterized by spectroscopic studies and HPLC. The morphological characterization of the mild steel surface was performed by SEM. Our results demonstrated that all inhibitors showed the same inhibition efficiency if the normalization in peptide/protein amount was performed, indicating proteins/peptides as the class of molecules responsible for inhibiting corrosion. For example, for 100 mg L−1 in protein content, the inhibition efficiency was 84 and 82%, respectively, from electrochemical impedance and polarization curves results, and 89 and 93–94% after 2 and 24 h immersion time, respectively, from mass loss measurements. Polarization curves indicated that all inhibitors behave as a mixed-type inhibitor, more explicit for the cathodic branch. The SEM results suggest that all extracts promoted a protective action against corrosion of the mild steel in H2SO4 solution.

Convective heat transfer correlation for a single surrogate firebrand and a simplified firebrand pile on a flat plate using naphthalene sublimation in heated air flow

Previous studies have shown that most structure ignitions in wildland urban-interface fires are due to firebrand deposition and ignition. The heat transfer mechanisms involved in firebrand deposition need further study and characterization for better understanding of the firebrand ignition process. In particular, convective heat transfer correlations over a single firebrand and a pile of firebrands are lacking. Using the heat-mass transfer analogy, naphthalene sublimation experiments were conducted to determine convective heat transfer correlations for a single naphthalene cylinder (a surrogate firebrand) and an idealized three-firebrand pile resting on flat plates from mass loss measurements. These experiments were conducted in a wind tunnel using a heated (50 °C) or room temperature air flow (0.5 m/s to 2.1 m/s). There was good agreement between the Nusselt number correlation obtained using heated air and results with unheated airflows. Experiments using heated airflow reduced the experimental run times and uncertainty in mass loss measurements significantly. In general, the single firebrand had higher Nusselt numbers than the individual firebrands in the pile. In the three-firebrand pile, the firebrand at the top of the pile exhibited the highest heat transfer. The naphthalene sublimation technique can be easily extended to obtain convective heat transfer correlations for various firebrand geometries and configurations.

Nano-emulsification method as a strategy for oil soluble corrosion inhibitor transform to water soluble

Corrosion inhibitor is one of the most economical and effective approaches to protecting metal pipes in the oil and gas industries. However, a great amount of corrosion inhibitors such as imidazoline, are difficult to distribute fast due to their poor solubility or dispersibility in water, which results in inhomogeneous concentration distribution and ineffectiveness. In this study, nano-emulsification technique was developed to improve the dispersity of mercaptoacetic acid-modified oleic imidazoline (MOI) in corrosive water. The formulation of nanoemulsion is optimized with the phase inversion temperature (PIT) and droplet diameter. The prepared nanoemulsion which the hydrophilic lipophilic balance value (HLB) was 11.5 and the loading of corrosion inhibitor was 20 wt% exhibited remarkable water dispersion performance and its mean particle size was less than 100 nm. Moreover, its dispersion performance in water was significantly better than that of the paraffin oil system, and was similar in the ethanol system. The inhibition performances and mechanisms of nanoemulsion for L245 carbon steel in the H2S/CO2 containing 5.0 wt% NaCl solution were investigated with weight loss measurements and electrochemical tests. In terms of inhibition efficiency, the corrosion inhibitor encapsulated in nanoemulsion was exceeding 90%, which was comparable to the system employing ethanol and liquid paraffin as solvents. Further experimental results indicated that the nanoemulsion system was more consistent with the Freundlich adsorption model, unlike the other two systems which followed the Langmuir adsorption model. The morphology and composition of corrosion products were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods. The SEM and XPS results demonstrated that the nanoemulsion system did not change the material type of corrosion products, but had a visible influence on their morphology. In addition, the inhibition mechanism was also revealed by theoretical calculations. These findings suggest that nano-emulsification technique has the potential to improve the solubility or dispersibility of oil soluble corrosion inhibitor, thereby expanding its application fields.

Evaluation of skin barrier functions in patients with breast cancer-related lymphedema: Measurement of stratum corneum hydration, sebum level, and transepidermal water loss

Evaluation of skin barrier functions in patients with breast cancer-related lymphedema: Measurement of stratum corneum hydration, sebum level, and transepidermal water loss

Thermal Impedance Calibration for Rapid and Noninvasive Calorimetric Soft-Switching Loss Characterization

Virtual prototyping, multi-objective optimization and design automation are increasingly being used to meet the growing demands of modern power electronic applications in terms of efficiency and power density. These concepts are based on accurate loss models of the power semiconductors used. While for hard-switching the double pulse test is an established electrical characterization method, soft-switching losses can only be determined by calorimetric measurements. Despite significant improvements in using transient approaches, calorimetric characterization of soft-switching loss energy is very time-intensive and requires complex measurement setups. This paper presents a new automated calorimetric method with thermal impedance calibration that enables rapid and non-invasive switching loss measurements. Using ultra-fast transient measurements and accelerated cooling phases in between, soft-switching loss maps can be determined based on hundreds of individual readings. The proposed measuring method is validated against hard-switching electrical double pulse test measurements. The method achieves a maximum error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.9 \,\%$</tex-math></inline-formula> for the total loss measurement from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1-9 \,\mathrm{W}$</tex-math></inline-formula> and an average measurement error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$16.5 \,\%$</tex-math></inline-formula> for the soft-switching energy from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1-4 \,\mu \mathrm{J}$</tex-math></inline-formula> of wide bandgap power semiconductors. In addition to comparing the results of different semiconductor technologies for use in a charger application, the manufacturers' simulation models are also analyzed with respect to soft-switching energy.

Poster 357: Tranexamic Acid in Foot and Ankle Surgery: A Systematic Review and Meta-analysis

Objectives: Tranexamic acid (TXA) use has become common in Orthopedic surgeries. Despite the growing number of publications related to its use, no recent systematic reviews have been published examining TXA use in foot and ankle surgery. The aim of this review article is to provide a summary of the current available literature regarding TXA use in foot and ankle surgery and to further the understanding of its safety and efficacy. Methods: This was a systematic review following the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines as outlined on the PRISMA checklist. Databases utilized included PubMed, Ovid, CINAHL, Clinical Key, Medline, and Embase, and the search was conducted through May 21, 2022. Key words used in the search included: “tranexamic acid,” “TXA,” “foot,” “ankle,” “calcaneal,” and “surgery.” The outcomes within the studies analyzed included measures of perioperative blood loss (intra-operative blood loss, 24-hour postoperative blood loss, blood loss from hour 24 to hour 48, postoperative hemoglobin (Hgb), and postoperative hematocrit (Hct)), as well as wound complications and vascular events. Wound complications and vascular events were defined as infection, hematoma formation, necrosis, dehiscence, DVT, PE, myocardial infarction (MI), acute coronary syndrome (ACS), cardiovascular event (CVA), limb ischemia (LI), gastrointestinal hemorrhage (GIH), nerve damage, and any other conditions specified as wound complications or vascular events within individual studies. The Cochrane Collaboration’s Risk of Bias 2 (RoB2) tool was used to assess the risk of bias in the studies included. The quality of the studies included was scored using a modified Coleman methodology score (MCMS). Primary treatment outcomes having data from three or more studies available were summarized in forest plots using RevMan 5.4.1 software (The Cochrane Collaboration, Copenhagen, Denmark). Random-Effects models were used to calculate mean differences with 95% confidence intervals for each outcome measure. Heterogeneity of studies was assessed using Tau2, Chi2, and I2 statistics. Statistical significance was set at α=0.05 for all comparisons. Results: The literature search produced 1125 papers. The full texts of 16 studies were assessed using inclusion and exclusion criteria and seven studies met preliminary inclusion criteria. Upon further inspection, five met full inclusion criteria for the meta-analysis. All groups receiving TXA had statistically significantly lower blood loss values at 24 hours. One study found a statistically significant increase in blood loss from 24-48 hours in their A group (TXA) versus non-TXA. Three study groups demonstrated statistically significantly higher values of postoperative hemoglobin in patients receiving TXA versus patients not receiving TXA. Three study groups demonstrated statistically significantly higher values of postoperative hematocrit in patients receiving TXA versus patients not receiving TXA. No studies found statistically significant differences in wound complications between TXA and non-TXA groups. Conclusions: Despite a growing amount of literature on the topic, there is still a paucity of literature published on TXA use in foot and ankle surgery. Additional literature is required to determine the best strategy for TXA use to optimize patient outcomes. Current literature suggests that foot and ankle surgery patients treated with TXA may have reduced 24-hour postoperative blood loss, increased postoperative hemoglobin and hematocrit when compared to similar patients not receiving TXA. The use of TXA in foot and ankle surgery did not lead to increased thromboembolic complications.

Evaluating the adsorption and corrosion inhibition capabilities of Pyridinium - P - Toluene Sulphonate on MS in 1 M HCl medium: An experimental and theoretical study

Mild steel (MS) is a reasonably priced construction alloy that can be utilized for a broad array of tasks in a variety of settings, Viz. mild acidic conditions with minor precautions. The quantitative assessment of MS's corrosion behavior in 1 M acidic (HCl) medium, at temperatures between (298–328 K), both in the presence and absence of the inhibitor Pyridinium - P - Toluene Sulphonate (PPTS), was examined by utilizing weight loss (WL) measurement, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) methods. All these approaches were accompanied by surface characterization approaches utilizing scanning electron microscope (SEM) and atomic force microscope (AFM). This analysis is unique in that it uses WL approaches for each of the three indices to investigate the efficacy of a novel, reasonably priced, non-toxic, and environmentally friendly corrosion inhibitor (PPTS) for MS under 1 M acidic conditions. Significant corrosion resistance was achieved with the introduction of the tested inhibitor, and PPTS demonstrated a very promising inhibition efficiency (IE %) of 93.28% at 2 × 10−3 ppm at 298 K using the WL technique. The fluctuation in the kinetic and thermodynamic characteristics suggested that the PPTS was physically adsorbing to the MS, and its mixed-type inhibitive activity delayed both the cathodic as well as anodic processes following the Langmuir isotherm model. Furthermore, on the MS surface, the deposition of a highly protective layer was revealed by contact angle measurements. The implementation of quantum calculations (QC) and Monte Carlo simulation (MC) models produced insightful findings, and the outcomes were consistent with the outcomes of the experimental verdicts, indicating the possible corrosion inhibition characteristic of PPTS for MS in an HCl media.

Poster 193: Glenoid Bone Loss Evaluation: Utilization of Current Methods

Objectives: Preoperative evaluation of glenoid bone loss is essential in surgical planning and for patients’ expectations of their surgical outcome. The four literature backed methods for measuring glenoid bone loss include the chord method, percent diameter method, the intraoperative probe method, and Pico method. Using the intraoperative probe method, it has been suggested that 25% bone loss of the inferior glenoid may be the threshold of significant bone loss. In contrast, other studies show bone loss using percent diameter above 13.5-17.3% has been associated with significantly worse clinical outcomes. Differences in bone loss measurements method utilization can lead orthopedic surgeons to proceeding with soft-tissue stabilization in a high-risk patient or alternatively to an unnecessary osseous augmentation procedure. Therefore, it is important to understand how orthopedic surgeons measure bone loss. While 3D CT and the Pico method have been previously described as the gold standard in bone loss evaluation for their highest accuracy and interobserver reliability, it is unclear how most orthopedic surgeons evaluate for bone loss in their practice. The purpose of this study is to investigate how orthopedic surgeons measure glenoid bone loss. Methods: Based on existing literature, a 16-question survey was created by the senior author. This survey included questions investigating participants’ demographic information, typical surgical practice and volume, and glenoid bone loss identification method. The survey was sent out to members of the American Orthopedic Society for Sports Medicine (AOSSM) and Arthroscopy Association of North America (AANA). Results: One-hundred-seventy-two orthopedic surgeons responded to the survey with an average of 13.4 years in practice and average number of instability surgeries performed each year of 31.2 +/- 35. In regard to subspecialty, 137 participants completed a sports medicine fellowship, 18 completed a shoulder and elbow fellowship, 10 completed both a sports medicine and shoulder and elbow fellowship, 1 completed a sports medicine and pediatric sports medicine fellowship, and 1 completed a sports medicine and trauma fellowship (97% response rate). Responders were from a variety of geographic locations: 26% were from the Northeast, 30% were from the Midwest, 21% were from the South, 10% were from Mountain States, 10% were from the West Coast, 1 was from Hawaii, 1 was from Alaska, 1 was from Columbia, and 1 practiced in Italy (98% response rate). 46% of responders belong to a private practice, while 34% practice at an academic institution. An additional 16% reported a hospital- based practice, 2% reported military affiliation, and 2% work in a private practice with academic affiliations (99% response rate). 91.3% of responders said that they routinely measure glenoid bone loss. 3D CT was the imaging modality most commonly used for bone loss evaluation (125), followed by 2D MRI (86), X-rays (68), 2D CT (60), and 3D MRI (11) (Figure 1). The frequency of four common bone loss evaluation methods were analyzed: percent diameter loss was the most commonly used and was used routinely, the intraoperative probe length method was used occasionally, Pico method was used rarely, and the chord length method was used never (Figure 2). There was no significant effect of time in practice, practice location, and fellowship training on bone loss methods. Those in private practice or a medical group setting had a higher frequency of using the intraoperative probe length method. Conclusions: The result of this study suggests that there is significant inconsistency in how orthopedic surgeons evaluate and measure glenoid bone loss in the setting of shoulder instability. While physicians commonly use the most reliable imaging modality (3D CT), the most accurate literature backed method for evaluating bone loss (Pico method) is seldom used. Future research is necessary to understand the limiting factor for orthopedic surgeons to incorporate validated glenoid bone loss measurements into their practice and develop new automated methods to improve overall utilization.

Elemental sulfur corrosion of nickel-based alloy 825 in CO2–H2S-containing environment at high temperature and high pressure

The elemental sulfur corrosion resistance and corrosion mechanisms of nickel-based alloy 825 at high temperature and high pressure are still missing. This work investigates the elemental sulfur corrosion of nickel-based alloy 825 in CO2–H2S-containing environment at high temperature and high pressure using weight loss measurement, surface characterization and in-situ electrochemical techniques including electrochemical noise, electrochemical impedance spectroscopy as well as polarization curves. The results show that in the absence of elemental sulfur nickel-based alloy 825 hardly corrodes in the environment containing 0.5 MPa CO2 and 1.6 MPa H2S at 100 °C, since the passive film on the substrate could offer an enough protective performance. However, with the increasing elemental sulfur content, the corrosion of nickel-based alloy 825 becomes more and more obvious. Under the condition of full coverage of elemental sulfur, the uniform corrosion rate of the specimen can be as high as 0.327 mm/y. Moreover, under such a condition, serious localized corrosion could also be observed on the specimen surface. Based on results of electrochemical measurement and surface analysis, it is considered that underneath the elemental sulfur deposit the formation of a strong acidic environment generated from the hydrolysis of elemental sulfur largely destroys the passive film, leading to serious corrosion. Therefore, nickel-based alloy 825 used in high sulfur-containing environment should pay close attention to safety risk from elemental sulfur corrosion. The results of this work could provide a reference for the material selection in high sulfur natural gas field.

Citrus sinensis peel extract as corrosion inhibitor for mild steel in hydrochloric acid solution

This study investigated the corrosion inhibition properties of Citrus sinensis (CS) as a green inhibitor for mild steel in1 M HCl solution at different concentrations (100 mM, 150 mM and 200 mM). The corrosion behaviour of mild steel in the presence of absence of CS was evaluated using weight loss measurement, and scanning electron microscopy (SEM). Results of weight loss measurement showed that the corrosion rate of mild steel in 1 M HCl solution was significantly reduced with increasing concentrations of CS, inhibition efficiency reaching up to 98 %. SEM analysis revealed that the surface of mild steel in the presence of CS was covered a thin and homogenous protective film, while the surface of mild steel without CS was corroded and rough. An isothermal analysis was also carried out and the results indicated that the adsorption of CS on the mild steel surface followed the Freundlich isotherm equation. The value of n was found to be greater than 1, indicating that the adsorption of CS on the mild steel surface was favourable and increased with the inhibitor concentration. The value of the adsorption coefficient (Kf­) was found to be highest at 200 mM of CS, indicating a high adsorption capacity and strength of the CS on the mild steel surface

Improvements in mountain lake monitoring from satellite altimetry over the past 30 years – lessons learned from Tibetan lakes

Satellite altimetry has been widely used for inland water monitoring and modeling in the present decade. In this paper, the availability, data quality, and quantity of a number of spaceborne radar altimetry missions (including Topex/Poseidon (TP), ERS-2, Envisat, Jason-1/−2/−3, CryoSat-2, Saral, and Sentinel-3) are investigated. This is, to the best of our knowledge, the first paper to investigate the influences of onboard trackers, satellite flying directions, and land contamination on Level-1 waveforms and Level-2 measurements over large mountainous lakes. The analyses were conducted over eight Tibetan lakes, which are of varying sizes from ca. 93 to 1046 km2 and are sampled by multiple altimeters.From the results presented in this paper, it is demonstrated that the previous generation of altimeters, such as TP, Jason-1, ERS-2, and Envisat, shows a higher percentage of data unavailability and lower valid observation rates. Investigations of Level-1 waveforms show onboard tracker failing in locking on the lake surface, resulting in data loss or invalid measurements. In addition, the onboard tracking systems are sometimes unstable, resulting in larger along-track standard deviations (SD) (SD > 15 cm). In contrast, the recent generation of altimeters, i.e., Jason-3 and Sentinel-3 with open-loop tracking mode, significantly increases the data availability (> 90% passes and > 60% individual observations) and delivers higher precision measurements (SD around 10 cm). Moreover, the waveform leading edge is very consistent, indicating more stable onboard tracking. Higher quality Jason-3 and Sentinel-3 data allow monitoring of sub- and quasi-monthly lake variations, which are not revealed by e.g., TP and ERS-2 data due to poorer signal-to-noise ratios. Exceptionally, Saral Ka-band altimeter, operated in closed-loop tracking mode, is less affected by flying directions and land contamination (topography and landscapes), delivering high quality measurements (SD around 7 cm for 40 Hz).This study provides a comprehensive comparison of multiple altimeters in monitoring lakes in mountainous areas, and demonstrates the substantial improvements achieved in the past decades. However, care has to be taken when merging data from old generation altimetry missions over mountainous lakes. The lessons learned from these Tibetan lakes can be taken across to other mountain lakes.

Transmission loss measurement of recycled granular material using wave decomposition by impulse response extraction based on deconvolution

A simplified method for measuring transmission loss with a single fixed microphone inside an impedance tube is proposed. The separation of the incident wave from the reflected wave is achieved by deconvolving the loudspeaker driver voltage signal with the microphone signal to extract the impulse response. Random noise and a sinusoidal sweep signal were used as excitation signals for extraction of the impulse response, and two deconvolution methods were employed: linear deconvolution based on the adaptive LMS algorithm and simple spectral division. To avoid the overlap of incident and reflected pulses, a long impedance tube was used. Using a long impedance tube eliminates the need for an anechoic tube termination and the need to calibrate microphones. It is found that a reflective tube termination provides more accurate results compared to an approximately anechoic termination. The approximately anechoic termination shortens the available time window of the reflected pulse because it reflects some of the low-frequency sound. The standard deviation of the results and the dynamic range of the proposed method were determined experimentally. The applicability of the new method was tested on samples of unconsolidated granular material recycled from construction sites. The measured transmission losses of the different granular fractions were compared with a theoretical model for transmission losses at low frequencies. Samples consisting of smaller granule fractions were found to have surprisingly high transmission loss values. The design of the extended vertical impedance tube in combination with the proposed method is cost effective, speeds up the measurement procedure and provides reliable results.

Influence of Sr2+ ions on structural, optical and bioactive behaviour of phosphoborate glass system

Glass system having composition xSrO−3P2O5−21NaO−26CaO−(50-x)B2O3 (x = 0, 1, 2, 3 & 4 mol%) are synthesized via conventional melt quench method. Density and molar volume measurements are performed to examine the physical properties. Bioactivity of prepared samples is checked using phosphate buffer solution (PBSol) under static conditions at 37 °C. XRD, Infrared Spectroscopy and FESEM are used to analyze the assessment of hydroxyapatite (HAp) conversion. Analysis of XRD data indicates HAp formation. Optical absorption spectra are used to analyze optical band gap, refractive index and Urbach energy of the prepared composition. pH and weight loss measurements are also carried out to check the solubility of glasses. FESEM micrographs reveal visible change in morphology of glass after immersion in PBSol. Interpretations of observations as a function of composition and duration of soaking in PBSol have been done. pH values of PBSol, in which the samples were soaked for twelve days, showed enhancement in alkalinity, indicating the dissolution of the phospho-borate units in PBSol supporting the formation of HAp. Samples with higher SrO content show higher values of weight loss during the degradation in PBSol, suggesting their enhanced degradability in PBSol as compared to parent glass composition. Structural and morphological studies investigated by FESEM also predict the formation of HAp layer over glass surface. The developed compositions can be potential candidates for bone-bonding materials.

The Measurement and Analysis of the Hysteresis Loss in a Multifilament MgB2 Superconducting Wire

The article presents the results obtained from measuring the magnetization of and hysteresis loss in a multifilament MgB2 superconducting wire (produced by ASG Superconductors) for magnetic field applied in two directions: in parallel and perpendicular to the conductor axis. The measurement temperatures were varied in the range of 5–45 K. The MgB2 superconducting fraction magnetization curves were obtained by subtracting the magnetization of the wire ferromagnetic matrix measured at temperature T = 45 K, which is above the superconductor critical temperature Tc , from the magnetization value of the entire specimen. From these magnetization curves, the dependences of the hysteresis energy loss on the external magnetic field strength Qh(Н) were obtained. It is shown that, with the field oriented perpendicular to the MgB2 wire axis and at the external field characteristic values, the hysteresis loss is twice as large. A method for calculating the hysteresis loss in a superconducting wire and methods for reducing it are proposed. The obtained results can be used to optimize NMR and MRI facilities, superconducting motors and generators made using MgB2 superconducting wire produced by ASG Superconductors.

Snow Loss Into Leads in Arctic Sea Ice: Minimal in Typical Wintertime Conditions, but High During a Warm and Windy Snowfall Event

AbstractThe amount of snow on Arctic sea ice impacts the ice mass budget. Wind redistribution of snow into open water in leads is hypothesized to cause significant wintertime snow loss. However, there are no direct measurements of snow loss into Arctic leads. We measured the snow lost in four leads in the Central Arctic in winter 2020. We find, contrary to expectations, that under typical winter conditions, minimal snow was lost into leads. However, during a cyclone that delivered warm air temperatures, high winds, and snowfall, 35.0 ± 1.1 cm snow water equivalent (SWE) was lost into a lead (per unit lead area). This corresponded to a removal of 0.7–1.1 cm SWE from the entire surface—∼6%–10% of this site's annual snow precipitation. Warm air temperatures, which increase the length of time that wintertime leads remain unfrozen, may be an underappreciated factor in snow loss into leads.

Efficacy of an Oral Ageratum Conyzoides Formulation on Increasing Hair Growth and Decreasing Hair Loss in Males and Females: A Randomised Double-Blind Placebo-Controlled Study

Background Androgenetic alopecia (AGA) is associated with the enzyme 5a-reductase and prostaglandin D2, both of which are increased in bald areas of the scalp. We previously demonstrated the safety and efficacy of a topical Ageratum conyzoides (A. conyzoides) formulation in improving hair growth and decreasing hair loss. Objective A follow-up 12-week double-blind, randomised clinical trial investigating the efficacy and safety of A. conyzoides extract in an oral formulation, in males and females over 18-years of age. Methods 250 mg of A. conyzoides or a placebo was supplemented daily over a 12-week period to 84 healthy males or females with hair loss. The primary outcome was hair growth assessed by measuring hair density using HairCheck®, and hairline recession. Hair loss was measured by the mean number of hairs lost in a one-minute combing test and hair/tug pull test. Other assessments included Norwood/Hamilton and Ludwig-Savin scales evaluating male and female pattern baldness, respectively. Biochemical and haematological parameters were also assessed, as change from baseline for each group. Results Twelve (12)-week daily supplementation of A. conyzoides resulted in a significant reduction in hairline recession compared to the placebo group. A trend towards significance was observed for hair density between groups, where hair density increased in the A. conyzoides group and decreased in placebo group from their respective baseline values. No significant differences were found in hair loss measures or the Norwood/Hamilton and Ludwig-Savin scales. A significant difference was found in the change from baseline for total prostaglandins between groups at week 12, with a decrease from baseline in the active group and an increase in the placebo group. In males, a significant difference in the change from baseline was seen for type-2 5a-reductase, with a decrease from baseline in the active group and increase in the placebo group. Conclusion These results demonstrate an improvement in hair growth following the 12-week oral supplementation of A. conyzoides extract., with mechanistic convergence.